CALI 3.67-ft W x 27.3-ft L x 3 T Premium Felt Moisture Resistant Flooring Underlayment (100-sq ft / (Roll) in the Flooring Underlayment department at Lowes.com
Roberts 70-190 Super Felt Premium Felt Underlayment 100 sq.ft. - Amazon.com
RUBBER FELT Matting Insulation Carpet Underlay 1M X 1.37M Wide From a Roll | eBay
Underlay - Premier Plush Grey Multi 2' X 3' - Walmart.com
Underlay - Domestic and Commercial - Sargeant Carpets Bognor Regis